The high compacted density LiNi<sub>0.5-x</sub>Co<sub>0.2</sub>Mn<sub>0.3</sub>Mg<sub>x</sub>O<sub>2</sub> cathode material for lithium-ion batteries was syn...The high compacted density LiNi<sub>0.5-x</sub>Co<sub>0.2</sub>Mn<sub>0.3</sub>Mg<sub>x</sub>O<sub>2</sub> cathode material for lithium-ion batteries was synthesized by high temperature solid-state method, taking the Mg element as a doping element and the spherical Ni<sub>0.5</sub>Co<sub>0.2</sub>Mn<sub>0.3</sub> (OH)<sub>2</sub>, Li<sub>2</sub>CO<sub>3</sub> as raw materials. The effects of calcination temperature on the structure and properties of the products were investigated. The structure and morphology of cathode materials powder were analyzed by X-ray diffraction spectroscopy (XRD) and scanning electronmicroscopy (SEM). The electrochemical properties of the cathode materials were studied by charge-discharge test and cyclic properties test. The results show that LiNi<sub>0.4985</sub>Co<sub>0.2</sub>Mn<sub>0.3</sub> Mg<sub>0.0015</sub>O<sub>2</sub> cathode material prepared at calcination temperature 930°C has a good layered structure, and the compacted density of the electrode sheet is above 3.68 g/cm<sup>3</sup>. The discharge capacity retention rate is more than 97.5% after 100 cycles at a charge-discharge rate of 1C, displaying a good cyclic performance.展开更多
Mimicking the hierarchical structure of the skin is one of the most important strategies in skin tissue engineering.Monolayer wound dressings are usually not able to provide several functions at the same time and cann...Mimicking the hierarchical structure of the skin is one of the most important strategies in skin tissue engineering.Monolayer wound dressings are usually not able to provide several functions at the same time and cannot meet all clinical needs.In order to maximize therapeutic efficiency,herein,we fabricated a Tri-layer wound dressing,where the middle layer was fabricated via 3D-printing and composed of alginate,tragacanth and zinc oxide nanoparticles(ZnO NPs).Both upper and bottom layers were constructed using electrospinning technique;the upper layer was made of hydrophobic polycaprolactone to mimic epidermis,while the bottom layer consisted of Soluplus■ and insulin-like growth factor-1(IGF-1)to promote cell behavior.Swelling,water vapor permeability and tensile properties of the dressings were evaluated and the Tri-layer dressing exhibited impressive antibacterial activity and cell stimulation following by the release of ZnO NPs and IGF-1.Additionally,the Tri-layer dressing led to faster healing of full-thicknesswound in ratmodel compared to monolayer and Bilayer dressings.Overall,the evidence confirmed that the Trilayer wound dressing is extremely effective for full-thickness wound healing.展开更多
MXenes are emerging transition metal carbides and nitrides-based 2D conductive materials.They have found wide applications in sensors due to their excellent valuable properties.This paper reviews the recent research s...MXenes are emerging transition metal carbides and nitrides-based 2D conductive materials.They have found wide applications in sensors due to their excellent valuable properties.This paper reviews the recent research status of MXene-based electrochemical(bio)sensors for detecting biomarkers,pesticides,and other aspects.The first part of this paper introduced the synthesis strategy and the effect of surface modification on various prop-erties of MXenes.The second part of this paper discussed the application of MXenes as electrode modifiers for detecting pesticides,environmental pollutants,and biomarkers such as glucose,hydrogen peroxide,etc.Hope this review will inspire more efforts toward research on MXene-based sensors to meet the growing requirements.展开更多
The extraordinary strength of metal/graphene composites is significantly determined by the characteristic size,distribution and morphology of graphene.However,the effect of the graphene size/distribution on the mechan...The extraordinary strength of metal/graphene composites is significantly determined by the characteristic size,distribution and morphology of graphene.However,the effect of the graphene size/distribution on the mechanical properties and related strengthening mechanisms has not been fully elucidated.Herein,under the same volume fraction and distribution conditions of graphene,molecular dynamics simulations were used to investigate the effect of graphene sheet size on the hardness and deformation behavior of Cu/graphene composites under complex stress field.Two models of pure single crystalline Cu and graphene fully covered Cu matrix composite were constructed for comparison.The results show that the strengthening effect changes with varying the graphene sheet size.Besides the graphene dislocation blocking effect and the load-bearing effect,the deformation mechanisms change from stacking fault tetrahedron,dislocation bypassing and dislocation cutting to dislocation nucleation in turn with decreasing the graphene sheet size.The hardness of Cu/graphene composite,with the graphene sheet not completely covering the metal matrix,can even be higher than that of the fully covered composite.The extra strengthening mechanisms of dislocation bypassing mechanism and the stacking fault tetrahedra pinning dislocation mechanism contribute to the increase in hardness.展开更多
Magnesium(Mg)-based materials are a new generation of alloys with the exclusive ability to be biodegradable within the human/animal body.In addition to biodegradability,their inherent biocompatibility and similar-to-b...Magnesium(Mg)-based materials are a new generation of alloys with the exclusive ability to be biodegradable within the human/animal body.In addition to biodegradability,their inherent biocompatibility and similar-to-bone density make Mg-based alloys good candidates for fabricating surgical bioimplants for use in orthopedic and traumatology treatments.To this end,nowadays additive manufacturing(AM)along with three-dimensional(3D)printing represents a promising manufacturing technique as it allows for the integration of bioimplant design and manufacturing processes specific to given applications.Meanwhile,this technique also faces many new challenges associated with the properties of Mg-based alloys,including high chemical reactivity,potential for combustion,and low vaporization temperature.In this review article,various AM processes to fabricate biomedical implants from Mg-based alloys,along with their metallic microstructure,mechanical properties,biodegradability,biocompatibility,and antibacterial properties,as well as various post-AM treatments were critically reviewed.Also,the challenges and issues involved in AM processes from the perspectives of bioimplant design,properties,and applications were identified;the possibilities and potential scope of the Mg-based scaffolds/implants are discussed and highlighted.展开更多
Biocomposites as bio-inspired materials are produced from renewable resources that are organic and ecofriendly alternative materials.To improve the lifestyle of human beings as well as enhancing the environmental indi...Biocomposites as bio-inspired materials are produced from renewable resources that are organic and ecofriendly alternative materials.To improve the lifestyle of human beings as well as enhancing the environmental indices,functional bio-materials are now implemented in various promising industries.This work has systematically discussed and highlighted the implementations and trends of functional bionic materials in high tech industries,which are necessary for developing modern societies.Various medical,electronic,food and pharmaceutical applications have been considered.Bio-inspired materials are used to develop more sustainable possibilities to increase environmental conservation while maintaining customer satisfaction.Biopolymers were found employed in several sectors for various functional bio-products including organic thin-film transistors,organic phototransistor,emitting diodes,photodiodes,photovoltaic solar cells,hybrid dental resins,sustainable pharmaceuticals,and food packaging.They are used to create sustainable bio-products for energy storage and harvesting,bone regeneration,nerve damage repair,drug applications and various other industrial subcategories.展开更多
Coronaviruses are responsible for a developing budgetary,human and fatality trouble,as the causative factor of infections,for example,severe acute respiratory syndrome coronavirus 2(SARS-CoV-2).It has been well recogn...Coronaviruses are responsible for a developing budgetary,human and fatality trouble,as the causative factor of infections,for example,severe acute respiratory syndrome coronavirus 2(SARS-CoV-2).It has been well recognized that SARS-CoV-2 may survive under severe atmosphere circumstances.Hence,efficient containment approaches,for example,sanitizing,are crucial.Commonly,living compounds contribute a substance of chemical heterogeneity,with antiviral movement,and therefore can have efficacy as therapeutic tools toward coronavirus diseases.Here,in this review article,we have described the antimicrobialbased materials,which can be used to inhibit the spreading of the COVID-19.We have categorized these materials in three sections;(i)antimicrobial wall paint,(ii)antimicrobial papers and(iii)antimicrobial materials surface coating to be utilized as the antimicrobial-based materials for controlling the COVID-19.In the last section,we have given the concluding remarks with prospects in this area.展开更多
Sustainable agriculture plays a crucial role in meeting the growing global demand for food while minimizing adverse environmental impacts from the overuse of synthetic pesticides and conventional fertilizers.In this c...Sustainable agriculture plays a crucial role in meeting the growing global demand for food while minimizing adverse environmental impacts from the overuse of synthetic pesticides and conventional fertilizers.In this context,renewable biopolymers being more sustainable offer a viable solution to improve agricultural sustainability and production.Nano/micro-structural supramolecular biopolymers are among these innovative biopolymers that are much sought after for their unique features.These biomaterials have complex hierarchical structures,great stability,adjustable mechanical strength,stimuli-responsiveness,and self-healing attributes.Functional molecules may be added to their flexible structure,for enabling novel agricultural uses.This overview scrutinizes how nano/micro-structural supramolecular biopolymers may radically alter farming practices and solve lingering problems in agricultural sector namely improve agricultural production,soil health,and resource efficiency.Controlled bioactive ingredient released from biopolymers allows the tailored administration of agrochemicals,bioactive agents,and biostimulators as they enhance nutrient absorption,moisture retention,and root growth.Nano/micro-structural supramolecular biopolymers may protect crops by appending antimicrobials and biosensing entities while their eco-friendliness supports sustainable agriculture.Despite their potential,further studies are warranted to understand and optimize their usage in agricultural domain.This effort seeks to bridge the knowledge gap by investigating their applications,challenges,and future prospects in the agricultural sector.Through experimental investigations and theoretical modeling,this overview aims to provide valuable insights into the practical implementation and optimization of supramolecular biopolymers in sustainable agriculture,ultimately contributing to the development of innovative and eco-friendly solutions to enhance agricultural productivity while minimizing environmental impact.展开更多
Magnesium(Mg)alloys are gaining great consideration as body implant materials due to their high biodegradability and biocompatibility.However,they suffer from low corrosion resistance and antibacterial activity.In thi...Magnesium(Mg)alloys are gaining great consideration as body implant materials due to their high biodegradability and biocompatibility.However,they suffer from low corrosion resistance and antibacterial activity.In this research,semi-powder metallurgy followed by hot extrusion was utilized to produce the magnesium oxide@graphene nanosheets/magnesium(MgO@GNS/Mg)composite to improve mechanical,corrosion and cytocompatibility characteristics.Investigations have revealed that the incorporation of MgO@GNS nanohybrids into Mg-based composite enhanced microhardness and compressive strength.In vitro,osteoblast cell culture tests show that using MgO@GNS nanohybrid fillers enhances osteoblast adhesion and apatite mineralization.The presence of MgO@GNS nanoparticles in the composites decreased the opening defects,micro-cracks and micro-pores of the composites thus preventing the penetration of the corrosive solution into the matrix.Studies demonstrated that the MgO@GNS/Mg composite possesses excellent antibacterial properties because of the combination of the release of MgO and physical damage to bacterium membranes caused by the sharp edges of graphene nanosheets that can effectively damage the cell wall thereby facilitating penetration into the bacterial lipid bilayer.Therefore,the MgO@GNS/Mg composite with high mechanical strength,antibacterial activity and corrosion resistance is considered to be a promising material for load-bearing implant applications.展开更多
Incorporation of higher content Si anode material beyond 5 wt% to Li-ion batteries(LIBs)is challenging,owing to large volume change,swelling,and solid electrolyte interphase(SEI)instability issues.Herein,a strategy of...Incorporation of higher content Si anode material beyond 5 wt% to Li-ion batteries(LIBs)is challenging,owing to large volume change,swelling,and solid electrolyte interphase(SEI)instability issues.Herein,a strategy of diacetoxydimethylsilane(DAMS)additive-directed SEI stabilization is proposed for a stable operation of Si-0.33FeSi_(2)(named as Si-Fe)anode without graphite,which provides siloxane inorganics and organics enrichment that compensate insufficient passivation of fluoroethylene carbonate(FEC)additive and reduce a dependence on FEC.Unprecedented stable cycling performance of highly loaded(3.5 mA h cm^(-2))pure Si-Fe anode is achieved with 2 wt%DAMS combined with 9 wt%FEC additives under ambient pressure,yielding high capacity 1270 mA h g^(-1)at 0.5 C and significantly improved capacity retention of 81% after 100 cycles,whereas short circuit and rapid capacity fade occur with FEC only additive.DAMS-directed robust SEI layer dramatically suppresses swelling and particles crossover through separator,and therefore prevents short circuit,demonstrating a possible operation of pure Si or Sidominant anodes in the next-generation high-energy-density and safe LIBs.展开更多
The interfaces between the inorganic metal oxide and organic photoactive layer are of outmost importance for efficiency and stability in organic solar cells(OSCs).Tin oxide(SnO_(2))is one of the promising candidates f...The interfaces between the inorganic metal oxide and organic photoactive layer are of outmost importance for efficiency and stability in organic solar cells(OSCs).Tin oxide(SnO_(2))is one of the promising candidates for the electron transport layer(ETL)in high-performance inverted OSCs.When a solution-processed SnO_(2)ETL is employed,however,the presence of interfacial defects and suboptimal interfacial contact can lower the power conversion efficiency(PCE)and operational stability of OSCs.Herein,highly efficient and stable inverted OSCs by modification of the SnO_(2)surface with ultraviolet(UV)-curable acrylate oligomers(SAR and OCS)are demonstrated.The highest PCEs of 16.6%and 17.0%are achieved in PM6:Y6-BO OSCs with the SAR and OCS,respectively,outperforming a device with a bare SnO_(2)ETL(PCE 13.8%).The remarkable enhancement of PCEs is attributed to the optimized interfacial contact,leading to mitigated surface defects.More strikingly,improved light-soaking and thermal stability strongly correlated with the interfacial defects are demonstrated for OSCs based on SnO_(2)/UV cross-linked resins compared to OSCs utilizing bare SnO_(2).We believe that UV cross-linking oligomers will play a key role as interfacial modifiers in the future fabrication of large-area and flexible OSCs with high efficiency and stability.展开更多
The development of portable X-ray detectors is necessary for diagnosing fractures in unconscious patients in emergency situations.However,this is quite challenging because of the heavy weight of the scintillator and s...The development of portable X-ray detectors is necessary for diagnosing fractures in unconscious patients in emergency situations.However,this is quite challenging because of the heavy weight of the scintillator and silicon photodetectors.The weight and thickness of X-ray detectors can be reduced by replacing the silicon layer with an organic photodetectors.This study presents a novel bithienopyrroledione-based polymer donor that exhibits excellent photodetection properties even in a thick photoactive layer(~700 nm),owing to the symmetric backbone and highly soluble molecular structure of bithienopyrroledione.The ability of bithienopyrroledione-based polymer donor to strongly suppress the dark current density(Jd~10−10 A cm^(−2))at a negative bias(−2.0 V)while maintaining high responsivity(R=0.29 A W−1)even at a thickness of 700 nm results in a maximum shot-noise-limited specific detectivity of D_(sh)^(*)=2.18×10^(13)Jones in the organic photodetectors.Printed organic photodetectors are developed by slot-die coating for use in X-ray detectors,which exhibit D_(sh)^(*)=2.73×10^(12)Jones with clear rising(0.26 s)and falling(0.29 s)response times upon X-ray irradiation.Detection reliability is also proven by linear response of the X-ray detector,and the X-ray detection limit is 3 mA.展开更多
The research of rare earths for the synthesis of materials with improved mechanical performance is of great interest when they are considered for potential applications in the automotive industry. In this regard, the ...The research of rare earths for the synthesis of materials with improved mechanical performance is of great interest when they are considered for potential applications in the automotive industry. In this regard, the effect on the mechanical properties and microstmcture of the automotive A356 aluminum alloy reinforced with 0.2 （wt.%） AI-6Ce-3La （ACL） was investigated. The ACL was added to the melted A356 alloy in the as-received condition and processed by mechanical milling. In the second route, the effect of the ACL processed by mechanical milling and powder metallurgy techniques was investigated, and compared with the results ob- tained from the A356 alloy strengthened with ACL in the as-received condition. Microstmctural properties were evaluated by means of X-ray diffraction in order to observe the solubility of Ce/La in the A1 matrix. In addition, electron microscopy was employed in or- der to investigate the effect of milling time on the size and morphology of La/Ce phase under milling process. Mechanical properties of the A356 alloy modified with ACL were measured by hardness and tensile test. For comparison unmodified specimens of the A356 were characterized according to the previous procedure. The microstructural and mechanical characterization was carried out in specimens alter solution and artificial aging. Observations in scanning electron microscopy indicated a homogeneous dispersion of La/Ce phases by using both routes; however, mechanical results, in the modified A356 alloy with the ACL in the as-received condi- tion, showed an improvement in the mechanical performance of the A356 alloy over that reinforced with the ACL mechanically milled.展开更多
The microstructure and mechanical properties of 105 mm thick 5083 aluminum alloy hot rolled plate were investigated by metallurgical microscope, scanning electron microscope and tensile testing machine, and three majo...The microstructure and mechanical properties of 105 mm thick 5083 aluminum alloy hot rolled plate were investigated by metallurgical microscope, scanning electron microscope and tensile testing machine, and three major characteristic problems in mechanical properties inhomogeneity were explained. The results show that the mechanical properties of the rolled plate are inhomogeneous along the thickness direction. From the surface to the center, the strength shows an inverted "N" shape change and the elongation presents a semi "U" shape change. Several similar structural units composed of long fibrous grains(LFG) and short fibrous grains bands(SFGB) exist in a special layer(Layer 2) adjacent to the surface. This alternating layered distribution of LFG and SFGB is conducive to improving the plasticity by dispersing the plastic deformation concentrated on the boundary line(BL) between them. However, their different deformability will cause the alternation of additional stresses during the hot rolling, leading to the strength reduction. The closer the location to the center of the plate is, the more likely the recovery rather than the recrystallization occurs. This is the possible reason for the unnegligible difference in strength near the central region(Layer 4 and Layer 5).展开更多
The dissimilar joining of biodegradable magnesium alloy to pure commercial titanium by rotational friction welding with rotational speeds of 1100,1200 and 1300 r/min for the production of bio-screw was investigated.Th...The dissimilar joining of biodegradable magnesium alloy to pure commercial titanium by rotational friction welding with rotational speeds of 1100,1200 and 1300 r/min for the production of bio-screw was investigated.The metallographic analysis revealed that a good joining was obtained at the Ti/Mg alloy joint.On the magnesium alloy side,various regions such as the weld center zone(WCZ),dynamic recrystallization zone(DRX),thermo-mechanically affected zone(TMAZ)and partially deformed zone(PDZ)were observed.The highest tensile and shear strengths were 173 and 103.2 MPa,respectively at a rotational speed of 1300 r/min.The Ti/Mg alloy dissimilar friction welded joint failed at the vicinity of the intermetallic zone containing Ti3Al phase.The hardness values from the base metal magnesium alloy to the joining point increased mainly due to grain refinement(8.57μm in diameter)and the presence of titanium particles,while the hardness values were constant on the titanium side.It was also found that the corrosion rate of the Ti/Mg alloy joint was higher compared with that of the Ti and Mg alloy from the immersion studies.Additionally,the sample with a rotational speed of 1300 r/min showed better biocompatibility and a cell viability of 98.12%due to better corrosion resistance.展开更多
Hot tearing is often a major casting defect in magnesium alloys and has a significant impact on the quality of their casting products.Hot tearing of magnesium alloys is a complex solidification phenomenon which is sti...Hot tearing is often a major casting defect in magnesium alloys and has a significant impact on the quality of their casting products.Hot tearing of magnesium alloys is a complex solidification phenomenon which is still not fully understood,it is of great importance to investigate the hot tearing behaviour of magnesium alloys.This review attempts to summarize the investigations on hot tearing of magnesium alloys over the past decades.The hot tearing criteria including recently developed Kou’s criterion are summarized and compared.The numeric simulation and assessing methods of hot tearing,factors influencing hot tearing,and hot tearing susceptibility(HTS)of magnesium alloys are discussed.展开更多
Plasma electrolytic oxidation（PEO） was developed as a bond coat for air plasma sprayed（APS） nanostructure ZrO2 as top coat to enhance the corrosion resistance and antibacterial activity of Mg alloy. Corrosion beha...Plasma electrolytic oxidation（PEO） was developed as a bond coat for air plasma sprayed（APS） nanostructure ZrO2 as top coat to enhance the corrosion resistance and antibacterial activity of Mg alloy. Corrosion behavior and antibacterial activities of coated and uncoated samples were assessed by electrochemical tests and agar diffusion method toward Escherichia coli（E. coli） bacterial pathogens, respectively. The lowest corrosion current density and the highest charge transfer resistance, phase angle and impedance modulus were observed for PEO/nano-ZrO2 coated sample compared with those of PEO coated and bare Mg alloys. Nano-ZrO2 top coat which has completely sealed PEO bond coat is able to considerably delay aggressive ions transportation towards Mg alloy surface and significantly enhances corrosion resistance of Mg alloy in simulated body fluid（SBF） solution. Moreover, higher antibacterial activity was also observed in PEO/nano-ZrO2 coating against bacterial strains than that of the PEO coated and bare Mg alloys. This observation was attributed to the presence of ZrO2 nanoparticles which decelerate E. coli growth as a result of E. coli membranes.展开更多
The aim of this study was to evaluate the strain hardening and hot deformation behavior of asextruded Mg-Zn-Mn （ZM31） magnesium alloy with varying Y contents （0.3, 3.2, and 6 wt%） via compression testing along the...The aim of this study was to evaluate the strain hardening and hot deformation behavior of asextruded Mg-Zn-Mn （ZM31） magnesium alloy with varying Y contents （0.3, 3.2, and 6 wt%） via compression testing along the extrusion direction at room temperature, 200℃ and 300 ℃. Texture and phases were identified by X-ray diffraction. Alloy ZM31 ＋ 0.3Y consisted of a mixture of fine equiaxed grains and elon- gated grains with 1-phase （Mg3YZno）; alloy ZM31 ＋ 3.2Y contained 1-phase and W-phase （Mg3Y2Zn3）; alloy ZM31 ＋ 6Y had long-period stacking-ordered （LPSO） X-phase （Mg12YZn） and Mg24Y5 particles. With increasing Y content the basal texture became weakened significantly. While alloys ZM31 ＋ 0.3Y and ZM31 ＋ 3.2Y exhibited a skewed true stress-true stain curve with a three-stage strain hardening feature caused by the occurrence of {1072} extension twinning, the true stress-true stain curve of alloy ZM31 ＋ 6Y was normal due to the dislocation slip during compression. With increasing temperature the extent of skewness decreased. While the compressive yield stress, ultimate compressive stress, strain hardening exponent, and hardening capacity all decreased as the temperature increased, the retention of the high- temperature deformation resistance increased with increasing Y content mainly due to the presence of thermally-stable LPSO X-ohase.展开更多
This study was aimed at identifying underlying strengthening mechanisms and predicting the yield strength of as-extruded Mg-Zn-Y alloys with varying amounts of yttrium （Y） element. The addition of Y resulted in the ...This study was aimed at identifying underlying strengthening mechanisms and predicting the yield strength of as-extruded Mg-Zn-Y alloys with varying amounts of yttrium （Y） element. The addition of Y resulted in the formation of ternary 1 （Mg3YZn6）, W （Mg3Y2Zn3） and LPSO （Mg12YZn） phases which subse- quently reinforced alloys ZM31 ＋ 0.3Y, ZM31 ＋ 3.2Y and ZM31 ＋ 6Y, where the value denoted the amount of Y element （in wt%）. Yield strength of the alloys was determined via uniaxial compression testing, and grain size and second-phase particles were characterized using OM and SEM. In-situ high-temperature XRD was performed to determine the coefficient of thermal expansion （CTE）, which was derived to be 1.38 x 10^-5 K^-1 and 2.35 x 10^-5 K^-1 for W and LPSO phases, respectively. The individual strengthening effects in each material were quantified for the first time, including grain refinement, Orowan looping, thermal mismatch, dislocation density, load-bearing, and particle shearing contributions. Grain refinement was one of the major strengthening mechanisms and it was present in all the alloys studied, irrespective of the second-phase particles. Orowan looping and crE mismatch were the predominant strengthening mechanisms in the ZM31＋0.3Y and ZM31 ＋ 3.2Y alloys containing I and W phases, respectively, while load-bearing and second-phase shearing were the salient mechanisms contributing largely to the superior yield strength of the LPSO-reinforced ZM31 ＋ 6Y alloy.2017 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science ＆ Technology.展开更多
Infection is a major potential complication in the clinical treatment of bone injuries. Magnesium (Mg)-based composites are biodegradable and antibacterial biomaterials that have been employed to reduce infection foll...Infection is a major potential complication in the clinical treatment of bone injuries. Magnesium (Mg)-based composites are biodegradable and antibacterial biomaterials that have been employed to reduce infection following surgical implants. The aim of present study was to synthesize and in-vitro characterize Mg-based scaffolds containing silver for bone tissue engineering. Porous Mg-based scaffolds with four silver concentrations (i.e., 0, 0.5 wt.%, 1 wt.%, and 2 wt.%), denoted by Mg?Ca?Mn-Zn-xAg (MCMZ?xAg)(where x is the silver concentration), were fabricated by the space holder technique. The effects of silver concentration on pore architecture, mechanical properties, bioactivity, and zone of bacterial inhibition were investigated in-vitro. X-ray diffractometry (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and fluorescence microscopy were utilized to characterize the obtained scaffolds. In-vitro corrosion test results indicated that the MCMZ scaffolds with lower silver content were more resistant to corrosion than those enriched with higher amounts of silver. Examination of the antibacterial activity showed that the MCMZ?Ag scaffolds exhibited superb potential with respect to suppressing the growth of Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus), in the inhibition zone around the MCMZ?Ag scaffolds, with increasing in the amount of incorporated silver;however, higher amounts of silver increased the cytotoxicity. Taken together, the results of this study demonstrate that the porous 0.5 wt.% Ag-containing scaffolds with interconnected pores, adequate mechanical properties, antibacterial activity, and cell adhesion are promising with respect to the repair and substitution of damaged and diseased bones.展开更多
文摘The high compacted density LiNi<sub>0.5-x</sub>Co<sub>0.2</sub>Mn<sub>0.3</sub>Mg<sub>x</sub>O<sub>2</sub> cathode material for lithium-ion batteries was synthesized by high temperature solid-state method, taking the Mg element as a doping element and the spherical Ni<sub>0.5</sub>Co<sub>0.2</sub>Mn<sub>0.3</sub> (OH)<sub>2</sub>, Li<sub>2</sub>CO<sub>3</sub> as raw materials. The effects of calcination temperature on the structure and properties of the products were investigated. The structure and morphology of cathode materials powder were analyzed by X-ray diffraction spectroscopy (XRD) and scanning electronmicroscopy (SEM). The electrochemical properties of the cathode materials were studied by charge-discharge test and cyclic properties test. The results show that LiNi<sub>0.4985</sub>Co<sub>0.2</sub>Mn<sub>0.3</sub> Mg<sub>0.0015</sub>O<sub>2</sub> cathode material prepared at calcination temperature 930°C has a good layered structure, and the compacted density of the electrode sheet is above 3.68 g/cm<sup>3</sup>. The discharge capacity retention rate is more than 97.5% after 100 cycles at a charge-discharge rate of 1C, displaying a good cyclic performance.
基金support of Isfahan University of Medical Sciences(Project code No.#1401262).
文摘Mimicking the hierarchical structure of the skin is one of the most important strategies in skin tissue engineering.Monolayer wound dressings are usually not able to provide several functions at the same time and cannot meet all clinical needs.In order to maximize therapeutic efficiency,herein,we fabricated a Tri-layer wound dressing,where the middle layer was fabricated via 3D-printing and composed of alginate,tragacanth and zinc oxide nanoparticles(ZnO NPs).Both upper and bottom layers were constructed using electrospinning technique;the upper layer was made of hydrophobic polycaprolactone to mimic epidermis,while the bottom layer consisted of Soluplus■ and insulin-like growth factor-1(IGF-1)to promote cell behavior.Swelling,water vapor permeability and tensile properties of the dressings were evaluated and the Tri-layer dressing exhibited impressive antibacterial activity and cell stimulation following by the release of ZnO NPs and IGF-1.Additionally,the Tri-layer dressing led to faster healing of full-thicknesswound in ratmodel compared to monolayer and Bilayer dressings.Overall,the evidence confirmed that the Trilayer wound dressing is extremely effective for full-thickness wound healing.
文摘MXenes are emerging transition metal carbides and nitrides-based 2D conductive materials.They have found wide applications in sensors due to their excellent valuable properties.This paper reviews the recent research status of MXene-based electrochemical(bio)sensors for detecting biomarkers,pesticides,and other aspects.The first part of this paper introduced the synthesis strategy and the effect of surface modification on various prop-erties of MXenes.The second part of this paper discussed the application of MXenes as electrode modifiers for detecting pesticides,environmental pollutants,and biomarkers such as glucose,hydrogen peroxide,etc.Hope this review will inspire more efforts toward research on MXene-based sensors to meet the growing requirements.
基金Foundation of Northwest Institute for Nonferrous Metal Research(ZZXJ2203)Capital Projects of Financial Department of Shaanxi Province(YK22C-12)+3 种基金Innovation Capability Support Plan in Shaanxi Province(2023KJXX-083)Key Research and Development Projects of Shaanxi Province(2024GXYBXM-351,2024GX-YBXM-356)National Natural Science Foundation of China(62204207,12204383)Xi'an Postdoctoral Innovation Base Funding Program。
文摘The extraordinary strength of metal/graphene composites is significantly determined by the characteristic size,distribution and morphology of graphene.However,the effect of the graphene size/distribution on the mechanical properties and related strengthening mechanisms has not been fully elucidated.Herein,under the same volume fraction and distribution conditions of graphene,molecular dynamics simulations were used to investigate the effect of graphene sheet size on the hardness and deformation behavior of Cu/graphene composites under complex stress field.Two models of pure single crystalline Cu and graphene fully covered Cu matrix composite were constructed for comparison.The results show that the strengthening effect changes with varying the graphene sheet size.Besides the graphene dislocation blocking effect and the load-bearing effect,the deformation mechanisms change from stacking fault tetrahedron,dislocation bypassing and dislocation cutting to dislocation nucleation in turn with decreasing the graphene sheet size.The hardness of Cu/graphene composite,with the graphene sheet not completely covering the metal matrix,can even be higher than that of the fully covered composite.The extra strengthening mechanisms of dislocation bypassing mechanism and the stacking fault tetrahedra pinning dislocation mechanism contribute to the increase in hardness.
文摘Magnesium(Mg)-based materials are a new generation of alloys with the exclusive ability to be biodegradable within the human/animal body.In addition to biodegradability,their inherent biocompatibility and similar-to-bone density make Mg-based alloys good candidates for fabricating surgical bioimplants for use in orthopedic and traumatology treatments.To this end,nowadays additive manufacturing(AM)along with three-dimensional(3D)printing represents a promising manufacturing technique as it allows for the integration of bioimplant design and manufacturing processes specific to given applications.Meanwhile,this technique also faces many new challenges associated with the properties of Mg-based alloys,including high chemical reactivity,potential for combustion,and low vaporization temperature.In this review article,various AM processes to fabricate biomedical implants from Mg-based alloys,along with their metallic microstructure,mechanical properties,biodegradability,biocompatibility,and antibacterial properties,as well as various post-AM treatments were critically reviewed.Also,the challenges and issues involved in AM processes from the perspectives of bioimplant design,properties,and applications were identified;the possibilities and potential scope of the Mg-based scaffolds/implants are discussed and highlighted.
文摘Biocomposites as bio-inspired materials are produced from renewable resources that are organic and ecofriendly alternative materials.To improve the lifestyle of human beings as well as enhancing the environmental indices,functional bio-materials are now implemented in various promising industries.This work has systematically discussed and highlighted the implementations and trends of functional bionic materials in high tech industries,which are necessary for developing modern societies.Various medical,electronic,food and pharmaceutical applications have been considered.Bio-inspired materials are used to develop more sustainable possibilities to increase environmental conservation while maintaining customer satisfaction.Biopolymers were found employed in several sectors for various functional bio-products including organic thin-film transistors,organic phototransistor,emitting diodes,photodiodes,photovoltaic solar cells,hybrid dental resins,sustainable pharmaceuticals,and food packaging.They are used to create sustainable bio-products for energy storage and harvesting,bone regeneration,nerve damage repair,drug applications and various other industrial subcategories.
基金This investigation work was financially supported by the National Natural Science Foundation of China(21962008,51464028)Candidate Talents Training Fund of Yunnan Province(2017PY269SQ,2018HB007)Yunnan Ten Thousand Talents Plan Young&Elite Talents Project(YNWR-QNBJ-2018-346).
文摘Coronaviruses are responsible for a developing budgetary,human and fatality trouble,as the causative factor of infections,for example,severe acute respiratory syndrome coronavirus 2(SARS-CoV-2).It has been well recognized that SARS-CoV-2 may survive under severe atmosphere circumstances.Hence,efficient containment approaches,for example,sanitizing,are crucial.Commonly,living compounds contribute a substance of chemical heterogeneity,with antiviral movement,and therefore can have efficacy as therapeutic tools toward coronavirus diseases.Here,in this review article,we have described the antimicrobialbased materials,which can be used to inhibit the spreading of the COVID-19.We have categorized these materials in three sections;(i)antimicrobial wall paint,(ii)antimicrobial papers and(iii)antimicrobial materials surface coating to be utilized as the antimicrobial-based materials for controlling the COVID-19.In the last section,we have given the concluding remarks with prospects in this area.
基金support provided by the UKRI via Grant No.EP/T024607/1Royal Society via grant number IES\R2\222208.
文摘Sustainable agriculture plays a crucial role in meeting the growing global demand for food while minimizing adverse environmental impacts from the overuse of synthetic pesticides and conventional fertilizers.In this context,renewable biopolymers being more sustainable offer a viable solution to improve agricultural sustainability and production.Nano/micro-structural supramolecular biopolymers are among these innovative biopolymers that are much sought after for their unique features.These biomaterials have complex hierarchical structures,great stability,adjustable mechanical strength,stimuli-responsiveness,and self-healing attributes.Functional molecules may be added to their flexible structure,for enabling novel agricultural uses.This overview scrutinizes how nano/micro-structural supramolecular biopolymers may radically alter farming practices and solve lingering problems in agricultural sector namely improve agricultural production,soil health,and resource efficiency.Controlled bioactive ingredient released from biopolymers allows the tailored administration of agrochemicals,bioactive agents,and biostimulators as they enhance nutrient absorption,moisture retention,and root growth.Nano/micro-structural supramolecular biopolymers may protect crops by appending antimicrobials and biosensing entities while their eco-friendliness supports sustainable agriculture.Despite their potential,further studies are warranted to understand and optimize their usage in agricultural domain.This effort seeks to bridge the knowledge gap by investigating their applications,challenges,and future prospects in the agricultural sector.Through experimental investigations and theoretical modeling,this overview aims to provide valuable insights into the practical implementation and optimization of supramolecular biopolymers in sustainable agriculture,ultimately contributing to the development of innovative and eco-friendly solutions to enhance agricultural productivity while minimizing environmental impact.
文摘Magnesium(Mg)alloys are gaining great consideration as body implant materials due to their high biodegradability and biocompatibility.However,they suffer from low corrosion resistance and antibacterial activity.In this research,semi-powder metallurgy followed by hot extrusion was utilized to produce the magnesium oxide@graphene nanosheets/magnesium(MgO@GNS/Mg)composite to improve mechanical,corrosion and cytocompatibility characteristics.Investigations have revealed that the incorporation of MgO@GNS nanohybrids into Mg-based composite enhanced microhardness and compressive strength.In vitro,osteoblast cell culture tests show that using MgO@GNS nanohybrid fillers enhances osteoblast adhesion and apatite mineralization.The presence of MgO@GNS nanoparticles in the composites decreased the opening defects,micro-cracks and micro-pores of the composites thus preventing the penetration of the corrosive solution into the matrix.Studies demonstrated that the MgO@GNS/Mg composite possesses excellent antibacterial properties because of the combination of the release of MgO and physical damage to bacterium membranes caused by the sharp edges of graphene nanosheets that can effectively damage the cell wall thereby facilitating penetration into the bacterial lipid bilayer.Therefore,the MgO@GNS/Mg composite with high mechanical strength,antibacterial activity and corrosion resistance is considered to be a promising material for load-bearing implant applications.
基金supported by the National Research Foundation grants funded by the Ministry of Science and ICT of Korea(2021M3H4A3A02086211 and RS-2023-00217581).
文摘Incorporation of higher content Si anode material beyond 5 wt% to Li-ion batteries(LIBs)is challenging,owing to large volume change,swelling,and solid electrolyte interphase(SEI)instability issues.Herein,a strategy of diacetoxydimethylsilane(DAMS)additive-directed SEI stabilization is proposed for a stable operation of Si-0.33FeSi_(2)(named as Si-Fe)anode without graphite,which provides siloxane inorganics and organics enrichment that compensate insufficient passivation of fluoroethylene carbonate(FEC)additive and reduce a dependence on FEC.Unprecedented stable cycling performance of highly loaded(3.5 mA h cm^(-2))pure Si-Fe anode is achieved with 2 wt%DAMS combined with 9 wt%FEC additives under ambient pressure,yielding high capacity 1270 mA h g^(-1)at 0.5 C and significantly improved capacity retention of 81% after 100 cycles,whereas short circuit and rapid capacity fade occur with FEC only additive.DAMS-directed robust SEI layer dramatically suppresses swelling and particles crossover through separator,and therefore prevents short circuit,demonstrating a possible operation of pure Si or Sidominant anodes in the next-generation high-energy-density and safe LIBs.
基金the Partnership for Skills in Applied Sciences,Engineering and Technology(PASET)-Regional Scholarship Innovation Fund(RSIF)(World Bank PASET No.IP22-15)supported by the National Research Foundation(NRF)(NRF-2021R1A2C2091787 and NRF-2022M3H4A1A03076280)+1 种基金the Korea Research Institute of Chemical Technology(KRICT)of the Republic of Korea(No.KS2422-10)the National Research Council of Science and Technology(Grant No.Global-23-007)of Republic of Korea。
文摘The interfaces between the inorganic metal oxide and organic photoactive layer are of outmost importance for efficiency and stability in organic solar cells(OSCs).Tin oxide(SnO_(2))is one of the promising candidates for the electron transport layer(ETL)in high-performance inverted OSCs.When a solution-processed SnO_(2)ETL is employed,however,the presence of interfacial defects and suboptimal interfacial contact can lower the power conversion efficiency(PCE)and operational stability of OSCs.Herein,highly efficient and stable inverted OSCs by modification of the SnO_(2)surface with ultraviolet(UV)-curable acrylate oligomers(SAR and OCS)are demonstrated.The highest PCEs of 16.6%and 17.0%are achieved in PM6:Y6-BO OSCs with the SAR and OCS,respectively,outperforming a device with a bare SnO_(2)ETL(PCE 13.8%).The remarkable enhancement of PCEs is attributed to the optimized interfacial contact,leading to mitigated surface defects.More strikingly,improved light-soaking and thermal stability strongly correlated with the interfacial defects are demonstrated for OSCs based on SnO_(2)/UV cross-linked resins compared to OSCs utilizing bare SnO_(2).We believe that UV cross-linking oligomers will play a key role as interfacial modifiers in the future fabrication of large-area and flexible OSCs with high efficiency and stability.
基金granted by the Korea Research Institute of Chemical Technology(KRICT)of the Republic of Korea(No.2422-10)the National Research Foundation(NRF)(NRF-2021R1C1C2007445 and RS-2023-00280495)of Republic of Korea.
文摘The development of portable X-ray detectors is necessary for diagnosing fractures in unconscious patients in emergency situations.However,this is quite challenging because of the heavy weight of the scintillator and silicon photodetectors.The weight and thickness of X-ray detectors can be reduced by replacing the silicon layer with an organic photodetectors.This study presents a novel bithienopyrroledione-based polymer donor that exhibits excellent photodetection properties even in a thick photoactive layer(~700 nm),owing to the symmetric backbone and highly soluble molecular structure of bithienopyrroledione.The ability of bithienopyrroledione-based polymer donor to strongly suppress the dark current density(Jd~10−10 A cm^(−2))at a negative bias(−2.0 V)while maintaining high responsivity(R=0.29 A W−1)even at a thickness of 700 nm results in a maximum shot-noise-limited specific detectivity of D_(sh)^(*)=2.18×10^(13)Jones in the organic photodetectors.Printed organic photodetectors are developed by slot-die coating for use in X-ray detectors,which exhibit D_(sh)^(*)=2.73×10^(12)Jones with clear rising(0.26 s)and falling(0.29 s)response times upon X-ray irradiation.Detection reliability is also proven by linear response of the X-ray detector,and the X-ray detection limit is 3 mA.
基金support from CONACYT via PhD scholarship 290674 and 290604
文摘The research of rare earths for the synthesis of materials with improved mechanical performance is of great interest when they are considered for potential applications in the automotive industry. In this regard, the effect on the mechanical properties and microstmcture of the automotive A356 aluminum alloy reinforced with 0.2 （wt.%） AI-6Ce-3La （ACL） was investigated. The ACL was added to the melted A356 alloy in the as-received condition and processed by mechanical milling. In the second route, the effect of the ACL processed by mechanical milling and powder metallurgy techniques was investigated, and compared with the results ob- tained from the A356 alloy strengthened with ACL in the as-received condition. Microstmctural properties were evaluated by means of X-ray diffraction in order to observe the solubility of Ce/La in the A1 matrix. In addition, electron microscopy was employed in or- der to investigate the effect of milling time on the size and morphology of La/Ce phase under milling process. Mechanical properties of the A356 alloy modified with ACL were measured by hardness and tensile test. For comparison unmodified specimens of the A356 were characterized according to the previous procedure. The microstructural and mechanical characterization was carried out in specimens alter solution and artificial aging. Observations in scanning electron microscopy indicated a homogeneous dispersion of La/Ce phases by using both routes; however, mechanical results, in the modified A356 alloy with the ACL in the as-received condi- tion, showed an improvement in the mechanical performance of the A356 alloy over that reinforced with the ACL mechanically milled.
基金Project(2011DFR50950)supported by the International Science and Technology Cooperation Program of ChinaProject(51971183)supported by the National Natural Science Foundation of ChinaProject(cstc2019jcyj-msxmX0594)supported by the Natural Science Foundation of Chongqing,China。
文摘The microstructure and mechanical properties of 105 mm thick 5083 aluminum alloy hot rolled plate were investigated by metallurgical microscope, scanning electron microscope and tensile testing machine, and three major characteristic problems in mechanical properties inhomogeneity were explained. The results show that the mechanical properties of the rolled plate are inhomogeneous along the thickness direction. From the surface to the center, the strength shows an inverted "N" shape change and the elongation presents a semi "U" shape change. Several similar structural units composed of long fibrous grains(LFG) and short fibrous grains bands(SFGB) exist in a special layer(Layer 2) adjacent to the surface. This alternating layered distribution of LFG and SFGB is conducive to improving the plasticity by dispersing the plastic deformation concentrated on the boundary line(BL) between them. However, their different deformability will cause the alternation of additional stresses during the hot rolling, leading to the strength reduction. The closer the location to the center of the plate is, the more likely the recovery rather than the recrystallization occurs. This is the possible reason for the unnegligible difference in strength near the central region(Layer 4 and Layer 5).
文摘The dissimilar joining of biodegradable magnesium alloy to pure commercial titanium by rotational friction welding with rotational speeds of 1100,1200 and 1300 r/min for the production of bio-screw was investigated.The metallographic analysis revealed that a good joining was obtained at the Ti/Mg alloy joint.On the magnesium alloy side,various regions such as the weld center zone(WCZ),dynamic recrystallization zone(DRX),thermo-mechanically affected zone(TMAZ)and partially deformed zone(PDZ)were observed.The highest tensile and shear strengths were 173 and 103.2 MPa,respectively at a rotational speed of 1300 r/min.The Ti/Mg alloy dissimilar friction welded joint failed at the vicinity of the intermetallic zone containing Ti3Al phase.The hardness values from the base metal magnesium alloy to the joining point increased mainly due to grain refinement(8.57μm in diameter)and the presence of titanium particles,while the hardness values were constant on the titanium side.It was also found that the corrosion rate of the Ti/Mg alloy joint was higher compared with that of the Ti and Mg alloy from the immersion studies.Additionally,the sample with a rotational speed of 1300 r/min showed better biocompatibility and a cell viability of 98.12%due to better corrosion resistance.
基金the National Natural Science Foundation of China(Project 51531002,51474043)the Ministry of Science&Technology of China(2013DFA71070)+1 种基金the Ministry of Education of China(SRFDR 20130191110018)Chongqing Municipal Government(CSTC2013JCYJC60001,CEC project,Two River Scholar Project and The Chief Scientist Studio Project).
文摘Hot tearing is often a major casting defect in magnesium alloys and has a significant impact on the quality of their casting products.Hot tearing of magnesium alloys is a complex solidification phenomenon which is still not fully understood,it is of great importance to investigate the hot tearing behaviour of magnesium alloys.This review attempts to summarize the investigations on hot tearing of magnesium alloys over the past decades.The hot tearing criteria including recently developed Kou’s criterion are summarized and compared.The numeric simulation and assessing methods of hot tearing,factors influencing hot tearing,and hot tearing susceptibility(HTS)of magnesium alloys are discussed.
基金the Universiti Teknologi Malaysia (UTM) for providing research facilities and financial support under Grants No:(1)UTM-Research University Grant (RUG) (Q.J130000.2524.16H35),and (2)Nippon Sheet Glass (NSG) R.J130000.7324.4B300
文摘Plasma electrolytic oxidation（PEO） was developed as a bond coat for air plasma sprayed（APS） nanostructure ZrO2 as top coat to enhance the corrosion resistance and antibacterial activity of Mg alloy. Corrosion behavior and antibacterial activities of coated and uncoated samples were assessed by electrochemical tests and agar diffusion method toward Escherichia coli（E. coli） bacterial pathogens, respectively. The lowest corrosion current density and the highest charge transfer resistance, phase angle and impedance modulus were observed for PEO/nano-ZrO2 coated sample compared with those of PEO coated and bare Mg alloys. Nano-ZrO2 top coat which has completely sealed PEO bond coat is able to considerably delay aggressive ions transportation towards Mg alloy surface and significantly enhances corrosion resistance of Mg alloy in simulated body fluid（SBF） solution. Moreover, higher antibacterial activity was also observed in PEO/nano-ZrO2 coating against bacterial strains than that of the PEO coated and bare Mg alloys. This observation was attributed to the presence of ZrO2 nanoparticles which decelerate E. coli growth as a result of E. coli membranes.
基金the Natural Sciences and Engineering Research Council of Canada (NSERC)the AUTO21 Network of Centres of Excellence for providing financial support+10 种基金financial support by the Premier’s Research Excellence Award (PREA)NSERC-Discovery Accelerator Supplement (DAS) AwardAutomotive Partnership Canada (APC)Canada Foundation for Innovation (CFI)Ryerson Research Chair (RRC) programthe Ministry of Science and Technology of the People’s Republic of China (2014DFG52810)the National Great Theoretic Research Project of China (2013CB632200)the National Natural Science Foundation of China (Project 51474043)Ministry of Education of the People’s Republic of China (SRFDR 20130191110018)Chongqing Municipal Government (CSTC2013JCYJC60001)Chongqing Science and Technology Commission (CSTC2011gjhz50001) for their financial supports
文摘The aim of this study was to evaluate the strain hardening and hot deformation behavior of asextruded Mg-Zn-Mn （ZM31） magnesium alloy with varying Y contents （0.3, 3.2, and 6 wt%） via compression testing along the extrusion direction at room temperature, 200℃ and 300 ℃. Texture and phases were identified by X-ray diffraction. Alloy ZM31 ＋ 0.3Y consisted of a mixture of fine equiaxed grains and elon- gated grains with 1-phase （Mg3YZno）; alloy ZM31 ＋ 3.2Y contained 1-phase and W-phase （Mg3Y2Zn3）; alloy ZM31 ＋ 6Y had long-period stacking-ordered （LPSO） X-phase （Mg12YZn） and Mg24Y5 particles. With increasing Y content the basal texture became weakened significantly. While alloys ZM31 ＋ 0.3Y and ZM31 ＋ 3.2Y exhibited a skewed true stress-true stain curve with a three-stage strain hardening feature caused by the occurrence of {1072} extension twinning, the true stress-true stain curve of alloy ZM31 ＋ 6Y was normal due to the dislocation slip during compression. With increasing temperature the extent of skewness decreased. While the compressive yield stress, ultimate compressive stress, strain hardening exponent, and hardening capacity all decreased as the temperature increased, the retention of the high- temperature deformation resistance increased with increasing Y content mainly due to the presence of thermally-stable LPSO X-ohase.
基金the Natural Sciences and Engineering Research Council of Canada (NSERC)Ontario Trillium Scholarships (OTS) program for providing financial support+8 种基金financial support by the Premier’s Research Excellence Award (PREA)Canada Foundation for Innovation (CFI)Ryerson Research Chair (RRC) programthe Ministry of Science and Technology of China (2014DFG52810)National Great Theoretic Research Project of China (2013CB632200)National Natural Science Foundation of China (Project 51474043)Ministry of Education of China (SRFDR 20130191110018)Chongqing Municipal Government(CSTC2013JCYJC60001)Chongqing Science and Technology Commission (CSTC2011gjhz50001)
文摘This study was aimed at identifying underlying strengthening mechanisms and predicting the yield strength of as-extruded Mg-Zn-Y alloys with varying amounts of yttrium （Y） element. The addition of Y resulted in the formation of ternary 1 （Mg3YZn6）, W （Mg3Y2Zn3） and LPSO （Mg12YZn） phases which subse- quently reinforced alloys ZM31 ＋ 0.3Y, ZM31 ＋ 3.2Y and ZM31 ＋ 6Y, where the value denoted the amount of Y element （in wt%）. Yield strength of the alloys was determined via uniaxial compression testing, and grain size and second-phase particles were characterized using OM and SEM. In-situ high-temperature XRD was performed to determine the coefficient of thermal expansion （CTE）, which was derived to be 1.38 x 10^-5 K^-1 and 2.35 x 10^-5 K^-1 for W and LPSO phases, respectively. The individual strengthening effects in each material were quantified for the first time, including grain refinement, Orowan looping, thermal mismatch, dislocation density, load-bearing, and particle shearing contributions. Grain refinement was one of the major strengthening mechanisms and it was present in all the alloys studied, irrespective of the second-phase particles. Orowan looping and crE mismatch were the predominant strengthening mechanisms in the ZM31＋0.3Y and ZM31 ＋ 3.2Y alloys containing I and W phases, respectively, while load-bearing and second-phase shearing were the salient mechanisms contributing largely to the superior yield strength of the LPSO-reinforced ZM31 ＋ 6Y alloy.2017 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science ＆ Technology.
基金partial financial support to this research from the Saskatchewan Health Research Foundation (SHRF)
文摘Infection is a major potential complication in the clinical treatment of bone injuries. Magnesium (Mg)-based composites are biodegradable and antibacterial biomaterials that have been employed to reduce infection following surgical implants. The aim of present study was to synthesize and in-vitro characterize Mg-based scaffolds containing silver for bone tissue engineering. Porous Mg-based scaffolds with four silver concentrations (i.e., 0, 0.5 wt.%, 1 wt.%, and 2 wt.%), denoted by Mg?Ca?Mn-Zn-xAg (MCMZ?xAg)(where x is the silver concentration), were fabricated by the space holder technique. The effects of silver concentration on pore architecture, mechanical properties, bioactivity, and zone of bacterial inhibition were investigated in-vitro. X-ray diffractometry (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and fluorescence microscopy were utilized to characterize the obtained scaffolds. In-vitro corrosion test results indicated that the MCMZ scaffolds with lower silver content were more resistant to corrosion than those enriched with higher amounts of silver. Examination of the antibacterial activity showed that the MCMZ?Ag scaffolds exhibited superb potential with respect to suppressing the growth of Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus), in the inhibition zone around the MCMZ?Ag scaffolds, with increasing in the amount of incorporated silver;however, higher amounts of silver increased the cytotoxicity. Taken together, the results of this study demonstrate that the porous 0.5 wt.% Ag-containing scaffolds with interconnected pores, adequate mechanical properties, antibacterial activity, and cell adhesion are promising with respect to the repair and substitution of damaged and diseased bones.
